If you're on legit gh and a lot of AAS, especially tren, and you have other fat burners in the mix (clen,t3, ect) you're probably not going to gain fat even on a shitty diet. Of course if you're shoving 5k cal of ice cream down your face every day you very well may get fat, but you'll probably be able to get away with a reasonable diet with a generous amount of dirty foods in it.